1. Field of the Invention
This invention relates to a method of forming a charge-storage electrode of a semiconductor device, and more particularly to a method of forming a charge-storage electrode, in which a leakage current through a high dielectric film can be restrained and capacitance can be increased by forming a platinum film at a side wall and top area of a polysilicon charge-storage electrode.
2. Information Disclosure Statement
As semiconductor devices are integrated, cell size is rapidly reduced accordingly. In spite of the reduction of the cell size, a certain amount of capacitance in a storage node is a necessity for the cell operation in a semiconductor device like a Dynamic Random Access Memory(DRAM). Therefore establishing an advanced process and high reliability in a device is needed to minimize the area which the capacitor occupies, while securing the minimum capacitance required for the cell operation.
As a solution to fix this kind of problem, BST(Barium-Strontium Titanate) or PZT(Lead-Zirconium Titanate) is used for a high dielectric film. But in using these dielectric films having a high dielectric constant, stable metal like platinum which is non-reactive is required to maintain characteristics of low leakage current. References are made to FIG. 1 to show a prior art which uses to form a platinum charge-storage electrode of a semiconductor device.
As shown in FIG. 1, a previous method of manufacturing a charge-storage electrode of a semiconductor device in a prior art, comprises: forming an insulating film(3) on a silicon substrate(1) having a junction region(2), etching the insulating film(3) so that the junction region(2) is exposed to form a contact hole for a charge-storage electrode, filling the inside of the contact hole with a polysilicon film(4), depositing a titanium film or a tantalum film as a barrier metal film(5) on the resulting structure, sequentially depositing a platinum film(6) on the barrier metal film(5), consecutively patterning a portion of the platinum film(6) and the barrier metal film(5) to form the charge-storage electrode, forming a high dielectric film(7) on the resulting structure. At this time, the high dielectric film(7) becomes in direct contact with the barrier metal film poor in electrical properties at the side wall of the charge-storage electrode so that it becomes the main reason for the leakage current. In addition, due to the fact that a thick platinum should be deposited to secure a high capacitance at a small charge-storage electrode on the plane, it may result in peeling problem of the platinum film or difficulties in etching process.